MCP get_workflow_details returns empty workflow.tags for tagged workflows

Questions
1

Describe the problem/error/question

Hi everyone,

I’m trying to audit workflows through the n8n MCP server and I’ve run into an issue with workflow tags.

The main problem is that get_workflow_details is returning an empty workflow.tags array for workflows that definitely have tags assigned in the n8n UI.

From the MCP tools reference, get_workflow_details appears to be expected to return workflow.tags as an array of tags with id and name:

At the same time, other MCP functionality is working correctly:

  • search_workflows returns workflow results as expected
  • get_workflow_details returns the workflow itself
  • nodes, connections, settings, active state, trigger count, scopes, and other metadata are all returned correctly
  • the issue seems isolated to tags only

Because of that, this does not look like a general access or authentication failure.

What is the error message?

There is no explicit error message.

The MCP call succeeds, but workflow.tags is always returned as an empty array.

How we are accessing it

We are calling the instance-level MCP HTTP endpoint directly with a Bearer token and using the tools/call method.

We also tested this through both:

  • direct HTTP calls to the MCP endpoint

  • an internal audit script that uses the same MCP tools

Both paths produce the same result.

Steps to reproduce the issue

  1. Take a workflow that has one or more tags visible in the n8n UI.

  2. Call get_workflow_details for that workflow through the n8n MCP server.

  3. Inspect the workflow.tags field in the response.

  4. Observe that workflow.tags is returned as [].

What we expected

We expected workflow.tags to include the assigned workflow tags, since the MCP docs list workflow.tags in the output for get_workflow_details.

What we observed

workflow.tags is always empty, even when the workflow is tagged in the UI.

Additional context

We are aware that search_workflows does not document tags in its preview response, so that part is not the issue.

The issue is specifically that get_workflow_details seems to omit or fail to populate tags.

We also checked the public API docs and saw that workflow tags are a first-class concept, including the GET /workflows/{id}/tags endpoint:
https://docs.n8n.io/api/api-reference/
and the workflowTags:list scope:
https://docs.n8n.io/api/authentication/

So at the moment we’re trying to understand whether:

  • this is a known bug in the MCP implementation

  • there is a permission/scope nuance specific to workflow tags

  • or there is an MCP configuration requirement we are missing

Information on your n8n setup

  • n8n version: Version 2.20.7

  • Deployment type: Self-hosted

  • MCP access method: instance-level MCP HTTP endpoint

  • Authentication: Bearer token for MCP endpoint

2

Welcome @JeremyStorm!

This looks like a known gap in the MCP server implementation - the get_workflow_details tool likely doesn’t join the tags table when fetching workflow data, so it returns an empty array even when tags exist in the UI. As a workaround for your audit script, call the REST API directly instead:

GET /api/v1/workflows/{id} with your API key in the header returns the full workflow object including the tags array with both id and name. You can hit this endpoint with an HTTP Request node or a simple curl/fetch in your audit script.

For the MCP gap itself, it’s worth opening a GitHub issue at Issues · n8n-io/n8n · GitHub so the team can track it.

3

Thank you @nguyenthieutoan , the issue is being tracked here: Bug: MCP get_workflow_details returns empty workflow.tags for tagged workflows · Issue #31825 · n8n-io/n8n · GitHub